Sleep is a biological necessity. Humans must sleep to maintain their health. The American Academy of Sleep Medicine (“AASM”) recommends that adult humans receive seven or more hours of sleep per night. However, for some individuals, particularly those who suffer from or who may be suffering from various sleep disorders, such as sleep apnea or other sleep-related breathing disorders, insomnia, parasomnias, circadian rhythm sleep-wake disorders, and sleep-related movement disorders, this can prove difficult.
Through the use of electroencephalogram (“EEG”) technology, scientists have been able to measure stages of sleep. In particular, EEG technology enables a determination to be made as to which particular stage of sleep a person may be undergoing at any given time, such as rapid eye movement (“REM”) sleep or non-REM (“NREM”) sleep.
Over an average life-expectancy, one could expect to sleep for approximately 20 years and dream for approximately 5 years. While the vast majority of people experience dreams passively as a quasi-random set of experiences that happen to them and over which they have very little, if any, control, some people experience lucidity during their dream state. A lucid dream is a state in which one becomes aware that one is dreaming, and in many cases, they can control the dream experience. The ability to regularly have lucid dreams is quite rare. Some people, through the use of various mental exercises, are capable of inducing a lucid dreaming experience, though this often requires extensive practice and concentration, and even still only results in occasional lucid dreams.
During typical REM sleep, one experiences a primary state of consciousness that is concerned only with the immediate present. During wakefulness, human beings experience a secondary state of consciousness that introduces higher order cognitive functions such as self-reflective awareness, abstract thinking, and access to thoughts of both past and future. One way to think of lucid dreaming is as a state of sleep in which both primary and secondary states of consciousness exist simultaneously which allows the subject to become aware of the fact that he or she is dreaming during the dream. This awareness or lucidity can also provide the subject with the ability to exert control over the ongoing dream plot.
During sleep, human beings typically enter REM sleep (e.g., dream sleep) during approximately 25% of their overall sleep time. The remainder of sleep is spent in NREM sleep. NREM sleep is made up of three stages. A person experiences light sleep in the first stage, and deep sleep in the second and third stages. During deep sleep, it is difficult to awaken a person. Following deep sleep, individuals experience REM sleep.
The average human subject sleeps in 90-minute sleep cycles, typically having about five cycles throughout the night. During these cycles, one alternates between stages of NREM and REM sleep. The first REM period typically occurs approximately 70-90 minutes after one falls asleep and may last for about ten minutes. Subsequent REM periods typically occur every 90 minutes. Subjects typically experience progressively better quality REM periods as the night goes on. Such REM periods may be of a longer duration than earlier REM periods. A subject's final REM period of the night may last for up to an hour or more.
Recently, market trends have demanded wrist-worn smart devices, typically utilizing actigraphy. Actigraphy measures a subject's movement to determine whether the subject is awake or asleep. While such wrist-worn devices may be relatively accurate in detecting movement, they are limited in that, unlike EEG technology, they cannot detect particular stages of sleep that the user may be undergoing at a given time (e.g., light sleep, deep sleep, NREM sleep, REM sleep, etc.). Accordingly, such conventional devices are further limited with respect to the amount of sleep data that can be provided to subjects.
Additionally, it is known in the art that the best time for a subject to remember their dreams is within the first ninety seconds after waking up. During this time, the ability to recall dreams (e.g., dream recognition) is enhanced by keeping the subjects body in the same position that it was in when waking up. In order to preserve the memory of the dreams recalled, subjects will often keep a dream log, with entries contemporaneously recorded at the time of recollection. It is often desired to be capable of remembering dreams, some consider dreams to be valuable and insightful while others find the ability to recall dreams as amusing, exciting, and entertaining. Other times, a subject may wish to not remember a particular or persistent dream.
According to the American Sleep Apnea Association (“ASAA”), twenty-two million Americans suffer from sleep apnea, a sleep-related breathing disorder in which a subject stops breathing periodically throughout sleep, in some cases hundreds of times during a sleep session. Breathing may be paused for durations ranging from a few seconds to more than a minute. The pauses in breathing are followed by brief moments of awakening, which can disrupt sleep. Sleep apnea can occur during any state of sleep, but it is typically most harmful during REM sleep. Common signs and symptoms of sleep apnea include loud snoring and gasping or choking sounds during sleep, waking up with a dry mouth or sore throat, morning headaches, excessive sleepiness or fatigue, insomnia, attention problems, and irritability. There are three types of sleep apnea—obstructive sleep apnea (“OSA”), central sleep apnea, and complex sleep apnea—with OSA being the most common.
It is estimated that 80% of OSA cases go undiagnosed. This may be due in part to the fact that a person suffering from sleep apnea may be unaware that he or she has the condition. Such a person may need to rely on others, such as family members or friends, to monitor him or her while sleeping, to see whether the person experiences any unusual sleep activity that may be associated with sleep apnea (e.g., breathing cessation, loud snoring, and gasping or choking sounds during sleep).
Sleep apnea disturbs sleep and affects sleep quality. Those with sleep apnea may also experience other problematic conditions. In this regard, the ASAA states that untreated OSA can lead to such problems as high blood pressure, chronic heart disease, atrial fibrillation, stroke, and other cardiovascular problems. Additionally, OSA may be associated with type-2 diabetes and depression, and may increase one's risk for premature death. As noted by the ASAA, with sleep apnea leading to drowsiness, it also has been shown to be a factor in many traffic accidents as well as accidents involving heavy machinery.
Sleep apnea is commonly treated with a continuous positive airway pressure (“CPAP”) machine. Other treatments include special dental devices that are worn during sleep, avoiding sleeping on one's back, weight loss, and surgery. A potential sleep apnea patient may first visit a primary care physician (“PCP”) for a consultation. The PCP may then refer the patient to a pulmonologist for another consultation, who then may prescribe that the patient undergo a sleep study in which the patient spends one or more nights at a sleep center/sleep lab for the sleep study, which typically includes a polysomnogram (“PSG”). The PSG records the patient's brain activity, eye movement, heart rate, and blood pressure, as well as the amount of oxygen in the patient's blood, air movement through the patient's nose during breathing, snoring, and chest movements. This is typically accomplished through the use of multiple sensors and other equipment connected to the patient, such as electrodes, nasal tubing, elastic belts fitted around the chest and abdomen, a finger monitor, EKG monitors, and a microphone. Following the PSG, the patient may receive a diagnosis and, if diagnosed with sleep apnea, then may be prescribed a CPAP machine.
For many people, undergoing a sleep study in a sleep center/sleep lab is not ideal. Many people find it difficult to sleep in such an environment compared to sleeping at home. To avoid the need for patient to sleep at a sleep center/sleep lab for a PSG, home-based sleep tests have been used. However, such tests do not monitor brain activity, and therefore, are not complete PSG studies.